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Acanthosis nigricans - Anogenital in
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Acanthosis nigricans - Anogenital in

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Contributors: Kyle Cheng MD, Susan Burgin MD, Belinda Tan MD, PhD, David Foster MD, Mary Gail Mercurio MD, Lynne Margesson MD
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Synopsis

Acanthosis nigricans (AN) is a localized skin disorder manifesting with hyperpigmented, velvety plaques typically located in flexural and intertriginous regions. The precise pathogenesis is unknown but is speculated to involve the stimulation of insulin-like growth factor receptors and tyrosine kinase receptors on keratinocytes and fibroblasts.

AN can be classified into 8 types:

I. Obesity-associated – Most common, linked to diabetes, insulin resistance, high body mass index (BMI), metabolic syndrome, polycystic ovarian syndrome (PCOS).

II. Malignancy-associated / cutaneous paraneoplastic syndrome – Most commonly associated with gastric carcinoma, but numerous other malignancies have been reported. Elderly nonobese patients with new AN should have malignancy considered as a cause. Atypical (palmar, perioral, or mucosal) distributions or acute-onset AN may be more associated with malignancy.

III. Drug-induced – Niacin (nicotinic acid) is the most closely associated medication, but AN can also be caused by oral contraceptives, corticosteroids, diethylstilbestrol, heroin, fusidic acid, methyltestosterone, protease inhibitors, and folate.

IV. Syndromic – Type A refers to patients with HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndrome and acromegaly. Type B is typically seen in women who have uncontrolled diabetes mellitus and autoimmune diseases (systemic lupus erythematosus, scleroderma, Sjögren syndrome, and Hashimoto thyroiditis). This type is associated with the formation of antibodies against insulin receptors.

V. Acral – Affects elbows, knees, and knuckles. Typically seen in healthy sub-Saharan Africans.

VI. Unilateral – Also called nevoid. Usually represents an epidermal nevus in childhood.

VII. Benign – Rare autosomal dominant type developing at birth or during childhood.

VIII. Mixed – Any 2 or more of the above types combined.

Other related endocrinopathies include pituitary hypogonadism, thyroid disease, Addison disease, and acromegaly.

Codes

ICD10CM:
L83 – Acanthosis nigricans

SNOMEDCT:
402599005 – Acanthosis nigricans

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed: 12/06/2016
Last Updated: 01/13/2017
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Acanthosis nigricans - Anogenital in
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Acanthosis nigricans : Axilla, Hyperpigmented patch, Neck
Clinical image of Acanthosis nigricans
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